The aim of the proposed research is to investigate how children represent and combine words and concepts. The proposed four experiments are designed to answer three general questions. First, do children use words compositionally when they first acquire them? Second, do children build holistic or combinatorial representations of word combinations? Third, what are the rules of compositionally that children use? The experiment swill focus on children's developing adjective-noun combinations, but their results may apply to other word combinations as well. The first and second experiments will investigate how children extend novel adjectives across familiar and unfamiliar basic level category nouns by using a manual choice technique. If children extend novel adjectives across unfamiliar basic level nouns, then we may conclude that children use words compositionally when they are first acquired. The third experiment will explore how children represent combined concepts by employing preferentially headturning and search techniques. If children store features of individual constituents, then they probably have a compositional representation of word combinations. The four experiment will explore how children represent meanings of adjectives in relation to their head nouns by using manual choice. If children alter their representations of the same adjectives in different noun contexts, we may conclude that rather than storing an absolute referent for an adjective, children represent broad ranges of its possible values. This strategy, if found, might explain how children learn to combine the same adjective with different nouns.